Yeah, we saw that post as we were sending out our newsletter. Honestly, we're very excited about Joomla 4 using Bootstrap 5. It's the right thing to do and sets Joomla out on the right foot.
We will be updating JFBConnect v9 to use Bootstrap 5 as well. For our intents and purposes, the changes are pretty minor as BS5 extends BS4 mostly. I don't know exactly when that will be ready, and some of it will rely on Joomla beta 5 (assuming that's when BS5 is incorporated), but it will be coming.
Thanks!
Alex